CONSOLIDATED BALANCE SHEETS (USD $) In Thousands, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Current Assets:
Cash and cash equivalents	$ 106,609	$ 60,651
Restricted cash	27,761	21,412
Accounts receivable	59,501	79,008
Current portion of derivative instruments asset (Notes 6 and 7)	10,610	10,411
Inventory	18,214	18,628
Prepayments and other	23,647	7,615
Refundable income taxes	2,301	3,042
Total current assets	248,643	200,767
Property, plant, and equipment, net	1,549,626	1,388,254
Transmission system rights	178,319	180,282
Equity investments in unconsolidated affiliates (Note 3)	477,098	474,351
Other intangible assets, net	597,633	584,274
Goodwill	343,586	343,586
Derivative instruments asset (Notes 6 and 7)	16,589	22,003
Other assets	64,216	54,910
Total assets	3,475,710	3,248,427
Current Liabilities:
Accounts payable	20,561	18,122
Accrued interest	33,534	19,916
Other Accrued liabilities	41,456	43,968
Revolving credit facility (Note 5)	72,800	58,000
Current portion of long-term debt (Note 5)	246,520	20,958
Current portion of derivative instruments liability (Notes 6 and 7)	50,030	20,592
Dividends payable	10,921	10,733
Other current liabilities	1,278	165
Total current liabilities	477,100	192,454
Long-term debt (Note 5)	1,364,685	1,404,900
Convertible debentures	193,269	189,563
Derivative instruments liability (Notes 6 and 7)	109,873	33,170
Deferred income taxes	165,413	182,925
Power purchase and fuel supply agreement liabilities, net	46,811	71,775
Other non-current liabilities	60,022	57,859
Commitments and contingencies (Note 12)
Total liabilities	2,417,173	2,132,646
Equity
Common shares, no par value, unlimited authorized shares; 113,680,643 and 113,526,182 issued and outstanding at March 31, 2012 and December 31, 2011, respectively	1,217,893	1,217,265
Preferred shares issued by a subsidiary company	221,304	221,304
Accumulated other comprehensive income (loss)	12,216	(5,193)
Retained deficit	(395,743)	(320,622)
Total Atlantic Power Corporation shareholders' equity	1,055,670	1,112,754
Noncontrolling interest	2,867	3,027
Total equity	1,058,537	1,115,781
Total liabilities and equity	$ 3,475,710	$ 3,248,427